Location-based language learning

All of my DAP projects will have a language bent, and hopefully I will be able to use some of these applications in my classes to help my students with difficult topics. I have not worked out the details yet, but I would like to make one application which provides short language lessons (I will use Spanish and Portuguese to start) to users. Perhaps they could be triggered by location? Also, I know that I would like to make a cultural treasure hunt involving clues and data gathering and tying in the Hispanic and Luso cultural influences in New York. This would be really cool to use in a culture or language class.